Electrical conduit



(No Model.)

G. SPRAGUE. ELECTRICAL GONDUIT.

Patented May 6, 1890.

@fl/M W12 JVESSES UNITED STATES PATENT OFFICE..

GEORGE SPRAGUE, OF ALBION, NEV YORK.

ELECTRICAL CONDUIT.

SPECIFICATION forming part of' Letters Patent No. 427,445, dated May 6, 1890.

Application filed December 3, 1889. Serial No. 332,463. (No model.)

T0 all whom t 77u01/ concern:

Be it known that I, GEORGE SPRAGUE, a citizen of the United States, residing at Albion, in the county of Orleans and State of New York, have invented certain new and useful Improvements in Electrical Cond uit's, of which the vfollowing is a specification, reference being had therein to the accompanying drawings, in which- Figure 1 represents a longitudinal sectional view of one section of my conduit before being iilled with insulating material; Eig. 2, a similar view showing the conduit with passage-forming bars and end plates removed ready 'for use, the insulating material having hardened and set; Fig. 3, a transverse sectional view of Fig. l; Fig. 4, a section showing the water and electrically tight joint or connection between the conduit-sections; Fig. 5, a similar view of a short conduit-section provided with a flexible iilling and sectional removable easin g, whereby access may be had to the main wire cells or passages for the purpose of repairing, connecting, and removing wires, as will more fully hereinafter appear. Figs. 6 and 7 are respectively side and transverse sectional views of the same.

The objects and particular advantages of this invention will appear in the course of this specification.

In the drawings annexed, A designates a metal pipe of suitable length provided upon one end with an external right-hand screwthread and upon its other end with a lefthand screw-thread. This pipeis filled or lined with some non-conducting material, preferably glass, in the following manner: Plates a are fitted over the ends of the pipe and provided with as many holes there are to be wire leads or cells, five being shown in the drawings. Connecting these plates and holding them in position over the ends of the pipe are long cell-forming rods b, each rod being provided with a head at one end and a nut at the other end, the ends of the rods passing through the holes in the disks or plates and drawn tight by the nuts. These rods taper gradually from their head ends to their screwthreaded ends. rlhe molten glass or other insulating material is poured in through a suitable lling-aperture in one of theheads, as at a', the pipe being completely filled with the molten material. \Vhen the insulating compound has cooled and become hard and solid, the nuts on the ends of the rods are removed, after which the end plates and rods may be removed, the tapering formation of the rods greatlyfaeilitatin their withdrawal from the hardened material, the thicker ends of the rods being drawn out .ti rst.

The rods maybe provided with eyes,hooks, or handles b or other devices to enable them to be conveniently withdrawn.

Lateral. connection to the main cells or leads are formed, as shown-that is,short tapering rods c are connected to any one of the rods at the place where it is desired to form the lateral cell and extended out through the branch conduit c and held securely in place by being passed through holes in cap-plates c, placed over the ends of the branch conduits and having nuts tapped upon their outer ends. These rods c are provided with eyes through their inner ends, through which the main cell-rods pass. After the glass has set and hardened and the main rods withdrawn these short rods c (being formed tapering from their outer ends inwardly) may be readily withdrawn and the branch caps c removed. In this manner an eminently practical conduit is formed whose cost will be but a minimum and which will be practically indestructible.

Any number of wire cells or passages may be formed, as the exigencies of the case may require. The adjacent ends of the sections by means of the right and left screw-threads on their ends and by means of an internallythreaded coupling (l may be drawn tightly together without being twisted or turned.

letween the ends of the sections is placed a suitable elastic non-conducting packing m (such as rubber) provided with holes to correspond with the cells in the sections, this packing being clamped tightly between the ends of the sections by means of the threaded coupling (l. In this way an absolutely electrically tight and air and water tight joint is formed.

Rods or other means may be employed to cause the cells of one section to register with the cells of its adjacent sections, as is evident.

If found desirable, any other suitable means IOO may be employed to connect the adjacent ends of the sections together; but I prefer the means shown and described for the reasons stated.

At suitable points along the length of the conduit short sections A are inserted, as shown in Figs. 5, 6, and '7. This short section is constructed, preferably, of three sections of pipe e e c of the saine diameters as the main pipes, and connected thereto in the manner liereiiibefore described-tliat is, by a screw-coupliii g and interposed elastic washer. The sections c c e are connected together by internally-tlireaded couplings d d', the adjacent ends of the sections being provided with corresponding external screw-threads, as shown. The middle section c is divided longitudinally into two sections, whereby it may be removed at will by simply screwing back the coupling d d. The interiorof this short section A', instead of being filled with glass, as in constructing the main sectioiis,is filled with some iion-conducting pliable or elastic substance, preferably rubber, which is provided with wire-cells to correspond and register with the cells of the adjacent main sections. Formed in this elastic filling are radial slits, slots, or incisions f, which are of suitable length and extend from the respective cells or leads to the outside of the filling, these incisions being made in that port-ion of the elasticsection iiiclosed by the sectional section c. By iiiiscrewing the couplings d d the middle section c may be removed. Then by the use of a suitable hook the wires in the respective cells may be brought to the snrface through their respective slits for any desired purpose. The halves of the section c are then replaced and the couplings d d screwed over their ends, as before. These slits (which remain normally closed) are dcsigned particularly to provide for ready access to the main wire-cells to permit of the removal and insertion of wires in any of the cells, and also to permit of the coupling and uiieoiipliiig of any of the wires withoutdisturbing the main sections in the least. This improvement is therefore an important feature of this invention.

The plan of laying the conduit is preferably as follows: Take as many rods or needles as there may be cells in the conduit to be laid, these rods to be a couple of feet longer than the sections and small enough in diameter to readily pass through the cells. To one end of each of these needles attach a strong cord. Lay a section of conduit and through each of its cells insert a needle with a cord attached to its rear end until the forward ends of the needles protrude a short distance from the end of the section. Then insert the needles in the corresponding holes in the packing and the corresponding cells in the next conduit-section, placing' the end of the next section iii such proximity to the preceding section that when the needles are passed through the new section and protrude at its other end they will yet remain in the section already laid, thereby insuring the proper alignment of the respective cells. The threaded coupling is then screwed up ti glit, which will. draw the ends of the sections closely together against the packing. To insure the joint against moisture, the threads of the coupling should be well painted. Continue in this way until the entire conduit is laid, inserting lateral connections or branches and the short flexible sections wherever desired.

The wire may be easily drawn through the conduit-cells by means of the cords attached to the rear ends of the needles. In case a wire at any time be removed a cord should be attached to it and drawn into the cell by the removal of the wire.

The conduit maybe buried or placed in subways or passed from block to block through basements and cellars. Lateral wires may be conducted from the main circuit by the use of the lateral branch cells and conduits to buildings or other places, as may be desired, and there connected with insulated wires.

This conduit is suitable for bare wires, and,

as is evident, may be made with one or many cells to accommodate the number of wires dcsired.

I'laving described my invention, what I claim, and desire to secure by Letters Patent, is

l. A metallic pipe-section A, filled with a non-conducting substance and having a lateral branch c', also filled with said substance, this iioii-conductiiig material having formed in it one or more longitudinal tapering cells or passages and the material in the lateral branch being provided with an inwardly-tm pering` passage which communicates with one of the main cells or passages, substantially as and for the purpose described.

2. The combination of the elastic filling provided with longitudinal cells or leads and lateial slits or slots communicating with these cells or leads and a removable casing or pipe inclosing this elastic filling, substantially as described.

In testimony whereof I affix my signature in presence of two witnesses.

GEORGE SPRAGUE. lVitncsscs:

InviNe M. T iioiirsoiv, Sn'iii SPENCER.

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